The invention relates to steering-column locks of the electrically motorized type.
Many constructions of steering-column locks are known. First, steering-column locks have been proposed comprising a motor and a gearwheel which drives a locking bolt via a cam or a gradient associated with the gearwheel, wherein the gearwheel rotates about a shaft which is parallel to an output shaft of the electric motor, or else in which the gearwheel rotates about a shaft which is perpendicular to the output shaft of the electric motor.
The bolt then travels slidingly closer to the steering column, under the action of a profile arranged on the gearwheel, to a locked position of the steering column.
Conventionally, the bolt is designed to immobilize the shaft of the steering column by fitting into a longitudinal groove arranged on the contour of this shaft. For this purpose, the shaft comprises several grooves distributed angularly on its contour. The portions of the contour of the shaft separating two successive grooves are called teeth. When the bolt is in protruding position of interaction with the contour of the column shaft, it is either fitted into a groove for immobilizing this shaft, or in contact with a tooth. In the latter case, the column shaft is not prevented from rotating. However, as this is conventional, if the steering wheel connected to the shaft is operated, this shaft is automatically immobilized after a brief angular travel of the latter having the effect of placing a groove in line with the bolt so as to allow the latter to fit into this groove.
In the case of a motorized steering lock, it is essential to define positions called unlocking and locking positions in order to switch off the motor when they are reached. Accordingly, an indexing device and indexer associated with the bolt are provided, that is to say that the motor will be switched off only when the bolt has reached the unlocked position or the locked position. With respect to the position called the locked position, because the bolt may be either on a tooth or in a groove, two options can be used. The first option consists in defining the locked position for a bolt that is in a groove, this position corresponds to the lowest position of the bolt. If, in this indexation configuration of the locked position, the bolt is not in a groove but on a tooth, the bolt has not been able to reach its bottom position and therefore the locked position has not been able to be detected. The motor therefore continues to run. In order to prevent this phenomenon, it is therefore preferred to define the position called the locked position for a bolt that is on a tooth. In this indexation configuration of the locked position, the motor is stopped for a bolt position that has not reached the bottom level, that is to say in a groove. In order to compensate for this difference, provision is made to keep the motor running for a certain period of time. Unfortunately, with this additional rotation, the gearwheel risks reaching its position of abutment and causing a repetition of mechanical force on this abutment.